Wireless communications system, wireless communications method, wireless communications program and program recording medium

ABSTRACT

A dual mode mobile terminal has a dual mode in which said mobile terminal can be connected to any of two different wireless communications systems (hereinafter referred to as systems  1  and  2 ). The mobile terminal can be connected to optimum wireless communications system by considering conditions at which the mobile terminal is (moving speed, communication data rate) even if it is in the state of communicating using any of systems  1  and  2 . The mobile terminal ( 3 ) which can be connected to any of the system  1  having a wide service area and medium and low communication data rate and the system  2  having a local service area and high communication data rate determines whether or not it is in the service area of the systems  1  and  2 . Based upon the moving speed and/or the communication data rate of the current mobile terminal ( 3 ), the mobile terminal ( 3 ) is connected to the system  1  or  2  if the moving speed is higher or lower than a predetermined threshold, respectively, and is connected to the system  2  or  1  if the communication data rate is higher or lower than a predetermined threshold, respectively, irrespective of whether the mobile terminal is in the communicating state or not. Prior to connection, selection of the wireless system is informed to the user and the connection may be made in accordance with an instruction from the user.

TECHNICAL FIELD

The present invention relates to a wireless communications system,wireless communications method, wireless communications program andprogram recording medium. In particular, it relates to a wirelesscommunications system, wireless communications method, wirelesscommunications program and program recording medium which effectivelyachieve connection and switching (handoff or handover) of a mobileterminal to each wireless communications system, wherein the mobileterminal is capable of connecting to any of a plurality of differentwireless communications systems.

BACKGROUND OF THE INVENTION

Recently, technology of connection to the Internet has been drasticallyadvanced. In particular, both wireless communication services ofInternet access service having a wide communications service area andlow and medium communication data rate (not more than several hundredskbps), typically cellular type mobile wireless communications system(hereinafter referred to as the “cellular system”) and Internet accessservice having a local service area (a hot spot area having a diameterof several tens meters or an area of a diameter of several hundredsmeters such as shopping mall or urban densely built-up area which iscovered by overlapping hot spot areas) and high communication data rate(several tens Mbps), typically wireless local area network (herein afterreferred to as “WLAN system”) exhibit rapid developments.

The cellular system has features such as wide range and diversity incommunication service where as WLAN system has features such as highrate data communication and low charge (fixed charge). In order toeffectively use the features of both wireless communications systems,there is a need to merge two different wireless communications systemsof cellular type mobile wireless communications system and wirelesslocal area network system and to achieve switching (handoff)therebetween in a seamless manner.

Wireless communications systems which enable a mobile terminal which canbe connected and communicated to such two different wirelesscommunications systems to connect each different system and to beseamlessly switched therebetween are proposed in, for example, JapaneseLaid-Open Patent Publication No. H09-130405 (pages 13 to 14), JapaneseLaid-Open Patent Publication No. 2000-32032 (page 3) and JapaneseLaid-Open Patent Publication No. 2002-199426 (pages 5 to 7) In thetechnology which is disclosed in the above-mentioned specifications, adetermination whether or not switching between the wirelesscommunications systems is possible is made based upon the signalstrength and signal quality of the receiving signal of the mobileterminal or the position of the mobile terminal and then switchingbetween two different wireless communications systems is conducted.Seamless switching is achieved in such a manner that a user does notperceive the disconnection of communication and the generation ofswitching between wireless communications systems on switching.

However, the technologies which are disclosed in the above-mentionedspecifications do not sufficiently consider the features of eachwireless communications system and do not provide communications servicewhich is appropriate and convenient for users, depending upon theconditions of a mobile terminal (for example, the moving speed andcommunication data rate of the user's mobile terminal). If switching(handoff) between two different wireless communications systems isconducted based upon the signal strength and communication quality ofthe receiving signal, switching between a plurality of differentwireless communications systems is achieved in a seamless manner for auser depending upon the conditions concerning with the signal strengthand communication quality of receiving signal. However, appropriate andconvenient communications service is not necessarily provided since nocondition of the mobile terminal is not considered.

For example, if communication using a WLAN system which covers a localarea (hot spot area) is selected when a user moves at a high speed on ahighway or Shinkansen, then switching between access points (AP) of WLANsystem or WLAN service areas as well as switching between the cellularsystem and the WLAN system may frequently occur. This may imposeexcessive burden upon the processing load of the system control of eachwireless communications system and the communication processing load ofthe mobile terminal of a user. As a result, high data rate communicationbecomes impossible, as well as discontinuation of the communication mayoccur, so that communication service which is optimum and convenient forthe user can not be necessarily provided in some cases.

If the mobile terminal is in the service area which is simultaneouslycovered by two different wireless communications systems such as WLANsystem and cellular system and is connected with the cellular systemwhich covers a wide area so that it is in communication therewith, thenswitching to WLAN system which is capable of communicating at highcommunication data rate or at lower charge in a seamless manner is notpossible.

As stated in the above, since a high frequency range is used to achievea high data rate communication in WLAN system, the communication servicearea is local (range of several hundreds meters at most). In case ofcellular system, it is characterized by that the communication data rateis low and medium (several hundreds kbps at most), but the communicationservice area is wide so that it also covers the communication servicearea of WLAN system (some areas such as areas in building or undergroundareas may not be covered).

The prior art which conducts switching (handoff) between two wirelesscommunications systems such as WLAN system and cellular system havingforegoing different features depending upon the strength or quality ofreceiving signal without considering the each feature above may notprovide a result which is desirable for the users.

The present invention was made under such circumstances. It is an objectof the present invention to provide a wireless communications system,wireless communications method, wireless communications program, andprogram recording medium in two different communications systems such asa wireless communications system 1 having a wide service area and a lowand medium communication data rate, typically cellular system and awireless communications system 2 having a local service area and a highcommunication data rate, typically WLAN system, wherein the wirelesscommunications system, wireless communications method, wirelesscommunications program, and program recording medium enable a mobileterminal to select a wireless communications system which is optimum fora user by considering the user's request and mobile terminal conditionssuch as moving speed or communication data rate of user's mobileterminal, and to connecting the mobile terminal to selected wirelesscommunications system or to continue the communication by conductingswitching (handoff) between wireless communications system when themobile terminal is communicating with another wireless communicationssystem.

DISCLOSURE OF THE INVENTION

A first technical means resides in a wireless communications systemcomprising two different wireless communications systems which are awireless communications system 1 for medium and low data ratecommunication having a wide communication service area and a wirelesscommunications system 2 for high data rate communication having a localcommunication service area and mobile terminals which are connectable toany of said wireless communications systems 1 and 2, wherein said mobileterminals comprise; means for determining whether or not said mobileterminal is in the respective wirelessly communicative areas of saidwireless communications systems 1 and 2; means for detecting the movingspeed of said mobile terminal; and/or means for detecting thecommunication data rate of said mobile terminal; and means for switchingthe connection of the mobile terminal with said wireless communicationssystems 1 or 2 based upon a result of determining whether or not inservice areas and a result of detection of said moving speed detectingmeans and/or said communication data rate detecting means.

A second technical means resides in a wireless communications system asdefined in the first technical means, wherein said moving speeddetecting means detects the moving speed at which said mobile terminalmoves by calculating the Doppler frequency which is caused by themovement of said mobile terminal.

A third technical means resides in a wireless communications system asdefined in the first or second technical means, wherein saidcommunication data rate detecting means detects the communication datarate of said mobile terminal by calculating the transmission rate of thedata received and transmitted by said mobile terminal based upon thenumber of the transmitted or received data or the number of thetransmitted or received packets, which is collected at eachpredetermined measuring interval.

A fourth technical means resides in a wireless communications system asdefined in any of the first to third technical means, wherein if it isdetermined from a result of determination of said determining means thatsaid mobile terminal is in the communicative service areas of both ofsaid wireless communications systems 1 and 2, then the moving speed ofsaid mobile terminal which is detected by said moving speed detectingmeans is compared with a preset threshold; if said moving speed is equalto or higher than said threshold, said mobile terminal is connected tosaid wireless communications system 1; on the other hand, if said movingspeed is lower than said threshold, said mobile terminal is connected tosaid wireless communications system 2.

A fifth technical means resides in a wireless communications system asdefined in any of the first to fourth technical means, wherein if it isdetermined from a result of determination of said determining means thatsaid mobile terminal is in the communicative service areas of both ofsaid wireless communications systems 1 and 2 and said mobile terminal isconnected with said wireless communications system 1 so that it is inthe state of communicating therewith, then the moving speed of saidmobile terminal which is detected by said moving speed detecting meansis compared with a preset threshold; if said moving speed is equal to orhigher than said threshold, the connection between said mobile terminaland said wireless communications system 1 is maintained; on the otherhand, if said moving speed is lower than said threshold, the connectionis switched to said wireless communications system 2 by means of saidswitching means.

A sixth technical means resides in a wireless communications system asdefined in any of the first to fourth technical means, wherein if it isdetermined from a result of determination of said determining means thatsaid mobile terminal is in the communicative service areas of both ofsaid wireless communications systems 1 and 2 and said mobile terminal isconnected with said wireless communications system 2 so that it is inthe state of communicating therewith, then the moving speed of saidmobile terminal which is detected by said moving speed detecting meansis compared with a preset threshold; if said moving speed is equal to orhigher than said threshold, the connection is switched to said wirelesscommunications system 1 by means of said switching means; on the otherhand, if said moving speed is lower than said threshold, the connectionwith said wireless communications system 2 is maintained.

A seventh technical means resides in a wireless communications system asdefined in any of the first to fourth technical means, wherein if it isdetermined from a result of determination of said determining means thatsaid mobile terminal is in the communicative service areas of both ofsaid wireless communications systems 1 and 2 and said mobile terminal isconnected with said wireless communications system 1 so that it is inthe state of communicating therewith, then the communication data rateof said mobile terminal which is detected by said communication datarate detecting means is compared with a preset threshold; if saidcommunication data rate is equal to or higher than said threshold, theconnection is switched to said wireless communications system 2 by meansof said switching means; on the other hand, if said communication datarate is lower than said threshold, the connection with said wirelesscommunications system 1 is maintained.

An eighth technical means resides in a wireless communications system asdefined in any of the first to fourth technical means, wherein if it isdetermined from a result of determination of said determining means thatsaid mobile terminal is in the communicative service areas of both ofsaid wireless communications systems 1 and 2 and said mobile terminal isconnected with said wireless communications system 2 so that it is inthe state of communicating therewith, then the communication data rateof said mobile terminal which is detected by said communication datarate detecting means is compared with a preset threshold; if saidcommunication data rate is equal to or higher than said threshold, theconnection between said mobile terminal and said wireless communicationssystem 2 is maintained; on the other hand, if said communication datarate is lower than said threshold, the connection is switched to saidwireless communications system 1 by means of said switching means.

A ninth technical means resides in a wireless communications system asdefined in the seventh or eighth technical means, wherein switchingoperation to said wireless communications system 2 is conducted ifmoving speed of said mobile terminal which is detected by said movingspeed detecting means is lower than a preset threshold; switchingoperation to said wireless communications system 1 is conducted if saidmoving speed is equal to or higher than said threshold.

A tenth technical means resides in a wireless communications system asdefined in any of the first to ninth technical means, wherein if it isdetermined from a result of said determination of said determining meansand a result of comparison between said moving speed which is detectedby said moving speed detecting means and/or said communication data ratewhich is detected by said communication data rate detecting means andrespective preset threshold that said mobile terminal is to be connectedto said wireless communications system 1 or 2, or that connection ofsaid mobile terminal with said wireless communications system 1 or 2 isto be switched, said determined result is preliminarily informed to auser together with said determination result and said detection resultprior to connection or switching, so that said mobile terminal isconnected to said wireless communications system 1 or 2 which isselected by the user.

An eleventh technical means resides in a wireless communications methodwhich is conducted in a wireless communications system comprising twodifferent wireless communications systems which are a wirelesscommunications system 1 for medium and low data rate communicationhaving a wide communication service areas and a wireless communicationssystem 2 for high data rate communication having a local communicationservice area and mobile terminals which are connectable to any of saidwireless communications systems 1 and 2, wherein said mobile terminalsswitch the connection of the mobile terminal with said wirelesscommunications systems 1 or 2 based upon a result of determinationwhether said mobile terminal is in respective wirelessly communicativeareas of said wireless communications system 1 and 2 and results ofdetection of the moving speed and/or communication data rate of saidmobile terminal.

A twelfth technical means resides in a wireless communications method asdefined in the eleventh technical means, wherein if it is determinedthat said mobile terminal is in the communicative service areas of bothof said wireless communications systems 1 and 2, then the moving speedof said mobile terminal is compared with a preset threshold; if saidmoving speed is equal to or higher than said threshold, said mobileterminal is connected to said wireless communications system 1; on theother hand, if said moving speed is lower than said threshold, saidmobile terminal is connected to said wireless communications system 2.

A thirteenth technical means resides in a wireless communications methodas defined in the eleventh or twelfth technical means, wherein if it isdetermined that said mobile terminal is in the communicative serviceareas of both of said wireless communications systems 1 and 2 and saidmobile terminal is connected with said wireless communications system 1so that it is in the state of communicating therewith, then the movingspeed of said mobile terminal is compared with a preset threshold; ifsaid moving speed is equal to or higher than said threshold, theconnection between said mobile terminal and said wireless communicationssystem 1 is maintained; on the other hand, if said moving speed is lowerthan said threshold, then connection is switched to said wirelesscommunications system 2.

A fourteenth technical means resides in a wireless communications methodas defined in the eleventh or twelfth technical means, wherein if it isdetermined that said mobile terminal is in the communicative serviceareas of both of said wireless communications systems 1 and 2 and saidmobile terminal is connected with said wireless communications system 2so that it is in the state of communicating therewith, then the movingspeed of said mobile terminal is compared with a preset threshold; ifsaid moving speed is equal to or higher than said threshold, then theconnection is switched to said wireless communications system 1; on theother hand, if said moving speed is lower than said threshold, theconnection with said wireless communications system 2 is maintained.

A fifteenth technical means resides in a wireless communications methodas defined in the eleventh or twelfth technical means, wherein if it isdetermined that said mobile terminal is in the communicative serviceareas of both of said wireless communications systems 1 and 2 and saidmobile terminal is connected with said wireless communications system 1so that it is in the state of communicating therewith, then thecommunication data rate of said mobile terminal is compared with apreset threshold; if said communication data rate is equal to or higherthan said threshold, the connection is switched to said wirelesscommunications system 2; on the other hand, if communication data rateis lower than said threshold, then connection with said wirelesscommunications system 1 is maintained.

A sixteenth technical means resides in a wireless communications methodas defined in the eleventh or twelfth technical means, wherein if it isdetermined that said mobile terminal is in the communicative serviceareas of both of said wireless communications systems 1 and 2 and saidmobile terminal is connected with said wireless communications system 2so that it is in the state of communicating therewith, then thecommunication data rate of said mobile terminal is compared with apreset threshold; if said communication data rate is equal to or higherthan said threshold, the connection between said mobile terminal andsaid wireless communications system 2 is maintained; if saidcommunication data rate is lower than said threshold, the connection isswitched to said wireless communications system 1.

A seventeenth technical means resides in a wireless communicationsmethod as defined in the fifteenth or sixteenth technical means, whereinswitching operation to said wireless communications system 2 isconducted if said moving speed of said mobile terminal is lower than apreset threshold; switching operation to said wireless communicationssystem 1 is conducted if said moving speed is equal to or higher thansaid threshold.

An eighteenth technical means resides in a wireless communicationsmethod as defined in any of the eleventh to seventeenth technical means,wherein if it is determined from a result of determination of whetherthe mobile terminal is in the respective service area of said wirelesscommunications systems 1 and 2 and a result of comparison between saidmoving speed and/or said communication data rate and respective presetthreshold that said mobile terminal is to be connected to said wirelesscommunications system 1 or 2, or that connection of said mobile terminalwith said wireless communications system 1 or 2 is to be switched, saiddetermined result is preliminarily informed to a user together with saiddetermination result and said detection result prior to connection orswitching, so that said mobile terminal is connected to said wirelesscommunications system 1 or 2 which is selected by the user.

A nineteenth technical means resides in a wireless communicationsprogram, wherein said program executes a wireless communications methodas defined in any of the eleventh to eighteenth technical means by usingcomputer.

A twentieth technical means resides in a program recording medium,wherein said medium records thereon the wireless communications programas defined in the nineteenth technical means in such a manner that saidprogram can be read by computer.

In accordance with the first or eleventh technical means, the mobileterminal can immediately conduct wireless communication using any of thewireless communications systems even if the mobile terminal movesanywhere and the mobile terminal can select and communicate with awireless communications system which provides satisfactory communicationservice to users.

In accordance with the second and third technical means, the movingspeed and/or communication data rate of the mobile terminal can bealways detected by means of the moving speed detecting means and/orcommunication data rate detecting means of the mobile terminal andswitching between the wireless communications systems 1 and 2 can beconducted depending upon the user's situation by considering the movingspeed and/or communication data rate of the mobile terminal.

In accordance with the fourth and twelfth technical means, an optimumwireless communications system can be selected based upon the movingspeed of the mobile terminal if there is a request of connection forwireless communications from a user when the mobile terminal of the userexists in a service area which is simultaneously covered by the wirelesscommunications systems 1 and 2. In other words, since the mobileterminal can be connected to the wide area wireless communicationssystem 1 to prevent the local wireless communications system 2 frombeing selected if the mobile terminal moves at a high speed, frequentswitching can be prevented from occurring and stable communicationservice and communication data rate can be provided. If the mobileterminal moves at a low speed, it can be preferentially connected and itis possible to the wireless communications system 2 to obtain highcommunication data rate and low charge communication service.

In accordance with the fifth or thirteenth technical means, an optimumwireless communications system can be selected based upon the movingspeed of the mobile terminal even if the mobile terminal iscommunicating with the wireless communications system 1 when the mobileterminal of a user exists in the service area which is simultaneouslycovered by the wireless communications systems 1 and 2. In other words,if the mobile terminal moves at a high speed, communication with thewireless communications system 1 is maintained, so that switching tolocal wireless communications system 2 can be avoided. Hence, frequentswitching is prevented from occurring and stable communication serviceand communication data rate can be provided. On the other hand, if themobile terminal moves at a low speed, the system 1 can be preferentiallyswitched to the wireless communications system 2. It is thus possible toobtain high communication data rate and low charge communicationservice.

In accordance with sixth or fourteenth technical means, an optimumwireless communications system can be selected based upon the movingspeed of the mobile terminal even if the mobile terminal iscommunicating with the wireless communications system 2 when the mobileterminal of a user exists in the service area which is simultaneouslycovered by the wireless communications systems 1 and 2. In other words,if the mobile terminal moves at a high speed, switching to the wirelesscommunications system 1 can be preferentially conducted. Thereforefrequent switching of wireless communications system 2 can be avoided,and stable communication service and communication data rate can beprovided. If the mobile terminal moves at a low speed, communicationwith the wireless communications system 2 which is capable of high datarate communication is maintained and switching to the wirelesscommunications system 1 for low and medium data rate can be avoided.Thus, stable and high communication data rate can be assured.

In accordance with seventh or fifteenth technical means, an optimumwireless communications system can be selected based upon thecommunication data rate of the mobile terminal even if the mobileterminal is communicating with the wireless communications system 1 whenthe mobile terminal of a user exists in the service area which issimultaneously covered by the wireless communications systems 1 and 2.In other words, if the mobile terminal communicates at a high speed,switching to the wireless communications system 2 can be preferentiallyconducted. Hence, it is possible to obtain high communication data rateand low charge communication service. On the other hand, if the mobileterminal communicates at a low speed, communication with the system 1 ismaintained and switching to the local wireless communications system 2can be avoided. Thus, it is possible to prevent frequent switching fromoccurring, and to provide stable communication service and communicationdata rate even when the mobile terminal moves at a high speed.

In accordance with eighth or sixteenth technical means, an optimumwireless communications system can be selected based upon thecommunication speed of the mobile terminal even if the mobile terminalis communicating with the wireless communications system 2 when themobile terminal of a user exists in the service area which issimultaneously covered by the wireless communications systems 1 and 2.In other words, if the mobile terminal communicates at a high speed,communication with the wireless communications system 2 is maintained,so that switching to the wireless communications system 1 for low andmedium data rate can be avoided. Hence, high communication data rate andlow charge communication service can be continuously provided. On theother hand, if the mobile terminal communicates at a low speed,switching to the wireless communications system 1 can be conducted toprovide for high speed movement of the mobile terminal. Thus, it ispossible to provide stable communication service and communication datarate.

In accordance with the ninth or seventeenth technical means, switchingto optimum wireless communications system can be conducted based uponboth of the communication data rate and moving speed even when themobile terminal is communicating with the wireless communications system1 or 2. In other words, even if a condition of switching from thewireless communications system 1 to 2 occurs due to the fact that thecommunication data rate is high, communication with the wirelesscommunications system 1 is maintained without switching, and switchingto the local wireless communications system 2 can be avoided if themobile terminal moves at a high speed. Thus, it is possible to preventfrequent switching from occurring and to provide stable communicationsservice and communication data rate. On the other hand, even if acondition to switch from the wireless communications system 2 to 1occurs due to the fact that the communication data rate is low,switching to the wireless communications system 1, the charge of whichis generally high, can be avoided. Thus, it is possible to maintaincommunication with the wireless communications system 2 and to obtainlow charge communication service.

In accordance with the tenth or eighteenth technical means, selectioncondition of the wireless communications system can be preliminarilypresented to a user depending upon the moving speed and/or communicationdata rate of the mobile terminal prior to connection to the wirelesscommunications system 1 or 2, or prior to switching to the wirelesscommunications system 1 or 2. Thus, connection to the wirelesscommunications system which is desired by the user can be conducted inaccordance with the user's decision.

In accordance with the nineteenth technical means, it is possible tocontrol connection or switching for the wireless communications system 1or 2, so that it is possible to conduct connection or switching controlin a flexible manner. Moreover, in accordance with the twentiethtechnical means, flexible connection or switching control can be easilyachieved by obtaining commercially available program recording medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a network configuration view showing an example of a networkconfiguration of a wireless communications system of the presentinvention;

FIG. 2 is a block configuration view showing an example of a blockconfiguration which constitutes the inner structure of a mobile terminalwhich is shown in FIG. 1;

FIG. 3 is a processing flow chart explaining a process in which awireless communications system is selected when power supply of themobile terminal is turned on to initiate communication;

FIG. 4 is a processing flow chart explaining a process in which awireless communications system is selected involving switching when themobile terminal is communicating with the wireless communications system1; and

FIG. 5 is a processing flow chart explaining a process in which awireless communications system is selected involving switching when themobile terminal is communicating with the wireless communications system2.

PREFERRED EMBODIMENT OF THE INVENTION

An embodiments of a wireless communications system, a wirelesscommunications method, a wireless communications program and a programrecording medium of the present invention will now be described withreference to the drawings.

FIG. 1 shows a network configuration view showing an example of anetwork configuration of the wireless communications system of thepresent invention. A general view of the configuration of a networkcomprising a plurality of (two in the present embodiment) differentwireless communications systems is illustrated. In other words, it showsan example that the wireless communications system comprises; twodifferent wireless communications systems as a plurality of differentwireless communications systems which are a wireless communicationssystem 1 using a cellular type wireless communications system (cellularsystem) which provides a communications service having a wide servicearea and a medium and low communication data rate and a wireless localarea network system (WLAN system) which provides a communicationsservice having a local service area and a high communication data rate;and dual mode mobile terminals 3 which can be connected with both thewireless communications systems 1 and 2 for wireless communications. Themobile terminals 3 can be also connected with the Internet 4 via any ofthe wireless communications systems 1 and 2 in this example.

In other words, the wireless communications system 1 comprises acellular type mobile wireless communications system (cellular system)based on, for example, W-CDMA (wideband Code Division Multiple Access)scheme. The wireless communications system 1 covers a widecommunications service area and achieves a maximum data transfer rate of384 kbps outdoors and charges the service based upon the communicationsperiod of time or communication data amount. The system is capable ofproviding a service for users who move at high speed such as users onautomobiles or the Shinkansen. However, in accordance with the presentinvention, the wireless communications system 1 is not limited to onlyW-CDMA scheme, but may be other digital cellular type wide area wirelesscommunications systems such as GSM (Global System for MobileCommunications).

The wireless communications system 2 comprises a wireless local areanetwork system (WLAN system) of, for example, IEEE 802.11b or 802.11a orIEEE 802.11g standards (IEEE: Institute of Electrical and ElectronicsEngineers). The wireless communications system 2 covers a local servicearea (communications service areas are discrete and narrow) and achievesa maximum high data transfer rate of 54 Mbps. The system 2 usuallyadopts low or fixed economical charging system and provides the servicesfor users who move at low speed such as users who are stationary orwalking. However, in accordance with the present invention, the wirelesscommunications system 2 is not limited to only wireless local areanetwork system (WLAN system) of IEEE 802.11b or 802.11a or IEEE 802.11gstandard, but may be other high data rate wireless local area networksuch as UWB (Ultra Wideband) of next generation wireless local areanetwork which exceeds 100 Mbps or IEEE 802.11b, IEEE 802.11i, IEEE802.11j.

Base stations 11 a, 11 b, 11 c, . . . corresponding to respectivecommunications service area of cellular service areas 10 a, 10 b, 10 c,. . . which indicate a plurality of communications service areas (cells)in cellular system are provided in the wireless communications system 1as shown in FIG. 1 The antennas 12 a, 12 b, 12 c, . . . of the basestation receive and transmit radio wave signals from and to an antenna33 of the mobile terminal 3, respectively. Each of the base stations 11a, 11 b, 11 c, . . . is connected with a core network (CN) 14 through aradio access network (RAN) 13. The core network 14 comprises asubscriber relay exchange 15 a which connects to subscriber lines fromthe radio access network 13, a gate relay exchange 15 b which connectsto relay lines from each of the subscriber relay exchange 15 a to enableconnection with a gateway 18, a position information data base 16 whichregisters information on the position of each mobile terminal 3 andadvanced service control information data base 17 which registersinformation to control advanced communications service which is providedby the core network 14. The gateway relay exchange 15 b of the corenetwork 14 is connected to the Internet 4 through the gateway 18.

On the other hand, access points (APs) 21 a, 21 b, 21 c, . . .corresponding to respective communication service area of WLAN serviceareas 20 a, 20 b, 20 c, . . . which indicate a wireless communicationregions (cells) are provided in the wireless communications system 2 asshown in FIG. 1. The antennas 22 a, 22 b, 22 c of the access pointsreceive and transmit radio signals from or to the antenna 33 of themobile terminal 3. Each of the access points (APs) 21 a, 21 b, 21 c, . .. is connected to a WLAN (wireless local area network) center 24 via aWLAN (wireless local area network) access network 23. The WLAN center 24comprises a gateway router 25 which performs a gateway function forconnected WLAN access network 23, an authentication server 26 whichperforms authentication of each mobile terminal 3 and a WEB server 27which provides various information services. The gateway router 25 ofWLAN center 24 is connected to the Internet 4.

The mobile terminal 3 may be connected to any one of the wirelesscommunications systems 1 and 2 by a radio signal from the antenna 33 byusing a display unit 31 including a liquid crystal display and the likeand an input unit 32 including actuation keys and the like, so that itis possible through the connected wireless communications system 1 or 2to accesses the WEB server 41 which is connected to the Internet 4. Aunit 34 which determines whether or not the mobile terminal 3 is in theservice area of the wireless communications system 1 or 2, a movingspeed detecting unit 36 which detects the moving speed of the mobileterminal 3 and/or a communication data rate detecting unit 35 whichdetects the communication data rate of the mobile terminal 3 areincorporated in the mobile terminal 3 as will be described in detail.

Now, an example of a block configuration which constitutes the innerstructure of the mobile terminal 3 which is shown in FIG. 1 will bedescribed with reference to a block diagram of FIG. 2.

The mobile terminal 3 is formed with a dual mode transceiver which iscapable of communicating with any of two wireless communications i.e.the wireless communications systems 1 and 2. The antenna 1 33 a, radiounit 1 39 a ₂ and signal processing unit 1 39 a ₁ constitute atransceiver unit 1 39 a which corresponds to the wireless communicationssystem 1. The antenna 2 33 b, radio unit 2 39 b ₂ and signal processingunit 2 39 b ₁ constitute a transceiver unit 2 39 b which corresponds tothe wireless communications system 2. The antennas 1 33 a and 2 33 b maybe formed of a single dual frequency antenna. Switching between thetransceiver units 1 39 a and 2 39 b is conducted under control from awireless communications system switching unit 38.

Other units such as a terminal control unit 37, input unit 32 anddisplay unit 31 are common units of the mobile terminal 3 comprising adual mode transceiver. The terminal control unit 37 is adapted toperform the key input control of an input unit 32, screen displaycontrol of a display unit 31 and a battery control. It also performs thecontrol of the whole mobile terminal 3 including the control oftransceiver units 1 39 a and 2 39 b. Various programs such as userinterface software, and application software are executed by a terminalcontrol unit 37 having a main CPU.

Moreover, the terminal control unit 37 collects parameters whichrepresent respective communication quality of the signals which arereceived by the transceiver units 1 39 a and 2 39 b, such as BER (BitError Rate), BLER (Block Error Rate), SNR (Signal To Noise Ratio) andalso RSSI (Receiving Signal Strength Indicator), and collectsinformation on whether or not the mobile terminal 3 is in the servicearea, which is determined by the determining unit 34 based upon thecollected communication quality and signal strength and further collectsinformation on moving speed of the mobile terminal 3 from the movingspeed detecting unit 36 and information on communication data rate fromthe communication data rate detecting unit 35.

The terminal control unit 37 comprehensively may consider collectedinformation on communication quality, signal strength, information onwhether the terminal is in the service area, moving speed and/orcommunication data rate, display on the display unit 31 a result ofdetermination for selecting a proper wireless communications system,detect a result of selection which is entered by a user from the inputunit 32, and select a wireless communications system which is desired bya user by controlling the wireless communications system switching unit38 to switch between the transceiver units 39 a and 39 b. Alternatively,the terminal control unit 37 may select a proper wireless communicationssystem by controlling the wireless communications system switching unit38 to automatically switch between transceiver units 39 a and 39 b basedupon the result from the comprehensive consideration of the collectedinformation on whether the terminal is in the service area, informationon terminal moving speed and/or communication speed.

The moving speed detecting unit 36 is adapted to estimate the movingspeed at which the mobile terminal 3 moves. In order to estimate themoving speed of the mobile terminal 3, various approaches areapplicable. One approach involves calculating the Doppler frequencycaused by the movement of the mobile terminal 3 by detecting thevariations of the level of the envelope of receiving power due toRayleigh Fading to count the number of times when the level of theenvelope intersects the reference receiving power level in an upwarddirection, so that the moving speed of the mobile terminal 3, which isaveraged at regular intervals is calculated. Another approach involvesestimating the Doppler frequency based upon the pilot symbol in case ofW-CMDA.

The communication data rate detecting unit 35 can determine thecommunication data rate of the mobile terminal 3 by collecting thenumber of transmitted or received data (for example, the number oftransmitted or received bytes) or the number of transmitted or receivedpackets at regular intervals, to calculate the data transfer rate atwhich the mobile 3 transmits or receives the data. Thus thecommunication data rate of the mobile terminal 3 can be calculated.

Now, a process in which the mobile terminal 3 selects an appropriatewireless communications system will be described with reference toprocessing flow charts of FIGS. 3 through 5. Firstly, a process forselecting a wireless communications system when power supply of themobile terminal 3 is turned on to initiate communication will bedescribed with reference to a flow chart shown in FIG. 3.

When power to the mobile terminal 3 is turned on (step S1), search forbase station is conducted for the wireless communications system 1, sothat a base station having highest signal strength of pilot channelsignal, for example, a base station 11 a is selected for connection, sothat a report information from the base station 11 a is received andinitial processing such as attach processing is conducted (step S2).Subsequently, the mobile terminal 3 is brought into a standby mode atwhich periodical detection of signal reception and periodical positionregistration processing is conducted on a paging channel (step S3).

On the other hand, an initial processing is conducted in which an accesspoint (AP) is searched for the wireless communications system 2, so thatan access point having strongest periodical beacon signal, such asaccess point 21 a, is selected for connection (step S2). Subsequently,the mobile terminal 3 is brought into a standby mode in which theperiodical beacon signal is received for establishing synchronization(step S3).

If a request for connection of communication is issued by a useractuating the input unit 32, for example, there is a request of accessto the WEB server 41 of the Internet 4 (YES at step S4), a determinationis made whether or not the mobile terminal 3 is in the serviceable areasof both the wireless communications systems 1 and 2. Such determinationmay be made by, for example, the unit for determining whether mobileterminal is in the service area 34, based upon a result of measurementof the signal strength of the signal which is received by the antennas33 a and 33 b (step S5). If mobile terminal 3 is determined as not beingin any service areas of both the wireless communications systems 1 and 2(NO at step S5), the mobile terminal 3 is returned to standby mode atstep S3 since it cannot meet the connection request from the user.

On the other hand, if a determination is made that the mobile terminalis in any of service areas of the wireless communications systems 1 and2 (YES at step S5), a further determination whether the terminal is inthe service area is made at next steps S6 and S7.

If a determination that the mobile terminal 3 is in the service area ofthe wireless communications system 1 and is out of the service area ofthe wireless communications system 2 is made (YES at step S6), it meansthat only the wide area cellular mobile wireless communications system(cellular system) of the wireless communications system 1 can be used,so that connection with the wireless communications system 1 isconducted (step S11). If a determination that the mobile terminal 3 isout of the service area of the wireless communications system 1 and isin the service area of the wireless communications system 2 (YES at stepS7), only narrow wireless local area network system (WLAN system) of thewireless communications system 2 can be used, so that connection withthe wireless communications system is conducted (step S14).

If there are two wireless communications systems i.e. wirelesscommunications systems 1 and 2 at the same time, in other words, if themobile terminal is in the service areas of both two wirelesscommunications systems (No at steps S6 and S7), the program will proceedto step S8.

The moving speed of the mobile terminal 3 which is averaged at regularintervals and is output from the moving speed detecting unit 36 iscompared with a threshold M which is predetermined as a reference. Ifthe moving speed of the mobile terminal 3 is equal to or higher than thethreshold M, for example, it is not lower than the threshold 50 km/h(YES at step S8), then it is determined that use of the wirelesscommunications system 2 for local communications which causes frequentswitching to the access points other than access point (AP) 21 a whileit enables high data rate communication and low charges (it may befixed) does not provide any merits to users, so that connection with thewireless communications system 1 is automatically conducted (step S11).

On the contrary, if the moving speed of the mobile terminal 3 is lowerthan the threshold M, for example, lower than lower than 50 km/h (NO atstep S8), then it is determined that use of the wireless communicationssystem 2 for local communication which enables high data ratecommunication with low charges provides merits for users, so thatconnection with the wireless communications system is automaticallyconducted (step S14).

Prior to automatic connection with the wireless communications systems 1and 2 at steps S11 and S14, respectively, an situation whether themobile terminal 3 is in the service area, the moving speed of the mobileterminal 3, a result of selection between the wireless communicationssystem 1 and 2 may be displayed on the display unit 31 (step S9 or S12)to enable a user to select the connection with desired wirelesscommunications system as mentioned above (as shown by a dotted line inFIG. 3). In other words, if a user enters an instruction to permit theconnection with the wireless communications system in accordance withthe result of automatic selection from the input unit 32 based upon adisplay on the display unit 31 (YES at step S10 or S13), connection withautomatically selected wireless communications system is conducted (stepS11 or S14). If the user enters an instruction which is different fromthe result of automatic selection regarding the connection to thewireless communications system (NO at step S10 or S13), connection withthe wireless communications system which is different from theautomatically selected wireless communications system may be conducted(step S14 or S11)

Now, a process for selecting a wireless communications system whichinvolves a switching (handoff) operation when the mobile terminal 3 isin a communicating state will be described with reference to processingflow charts of FIGS. 4 and 5. FIGS. 4 and 5 show that the mobileterminal 3 is in the communicating state using the wirelesscommunicating systems 1 and 2, respectively.

If the mobile terminal 3 is in the communicating state using thewireless communications system 1 as shown in FIG. 4 (step S21),information on the result of respective determinations whether themobile terminal 3 is in the service areas of wireless communicationssystems 1 and 2, communication quality and field strength of thereceiving signals of the wireless communications systems 1 and 2, themoving speed and communication data rate of the mobile terminal 3 isupdated (step S22). Thereafter, a determination whether a switching(handoff) of cellular service areas (cells) in the same wirelesscommunications system i.e. the wireless communications system 1 isnecessary or not is made by detecting operation of peripheral basestations in cellular service areas (step S23).

If it is determined that a switching is necessary (YES at step S23),switching between the cellular service areas of the wirelesscommunications system 1 is conducted by switching the cells in thetransceiver unit 1 39 a (step S24) and program sequence will return toprocessing at step S22. If there is no necessity to switch between thecellular service areas of the wireless communications system 1 (NO atstep S23), a determination whether the mobile terminal 3 is also in theservice area of the wireless communications system 2 (step S25) is made.If the mobile terminal 3 is not in the service area of the wirelesscommunications system 2 (NO at step S25), then the program will proceedto processing at step S22 to continue the communication using thewireless communications system 1.

On the contrary, if the mobile terminal 3 is also in the service area ofthe wireless communications system 2 (YES at step S25), the moving speedof the mobile terminal 3 is detected by the moving speed detecting unit36. If the moving speed is lower than a predetermined threshold N, forexample, lower than 50 km/h which is equal to said threshold M (YES atstep S26), it is determined that use of the local area wirelesscommunications system 2 which enables high data rate communication withlow charges provides merits to user and switching (handoff) from thewireless communications systems 1 to 2 is automatically conducted (stepS29). Alternatively, if the mobile terminal is also in the service areaof the wireless communications system 2 (YES at step S25), thecommunication data rate of the mobile terminal 3 is detected by thecommunication data rate detecting unit 35. If the communication datarate is not lower than a predetermined threshold K, for example, notlower than 250 kbps (YES at step S26), it is determined that use of thelocal area wireless communications system 2 which enables high data rateand low charge communication provides merits to users, so that switching(handoff) from the wireless communications systems 1 to 2 isautomatically conducted (step S29).

If the mobile terminal is switched from the wireless communicationssystems 1 to 2 based upon the communication data rate which is detectedby the communication data rate detecting unit 35, switching may beconducted only if the moving speed which is detected by using the movingspeed detecting unit 36 is lower than a predetermined threshold N. Inother words, it prepares for the possibility that even if connection isswitched to the wireless communications system 2 in which high data ratecommunication is possible when the moving speed is not lower than saidthreshold N, then frequent switching of WLAN service areas may occur,which may not only make it impossible to conduct desired high data ratecommunication but also result in the interruption of the communication.

The condition whether the mobile terminal 3 is in the service area, themoving speed and/or communication data rate of the mobile terminal 3selection result of switching (handoff) to the wireless communicationssystem 2 are displayed on the display unit 31 (step S27) enable the userto select connection to desired wireless communications system prior toautomatic process of switching (handoff) to the wireless communicationssystem 2 at step S29 as mentioned above (as shown by a dotted line inFIG. 4). In other words, if the user enters from the input unit 32 aninstruction to switch the connection to the wireless communicationssystem 2 according to the result of automatic selection based upon theresult of a display on the display unit 31 (YES at step S28), switchingto the wireless communications system 2 which is automatically selectedis conducted (step S29). On the other hand, if the user enters aninstruction to continue the connection with the wireless communicationssystem 1, which is different from the result of automatic selection fromthe input unit 32 (NO at step S28), the program sequence may proceed tostep S22 at which connection to the wireless communications system 1 iscontinued.

Now, operation when the mobile terminal 3 is in the state ofcommunicating using the wireless communications system 2, which issubstantially similar to the above-mentioned operation which is appliedwhen the mobile terminal 3 is in the state of communicating using thewireless communications system 1 shown in FIG. 4 will be described withreference to FIG. 5. If the mobile terminal 3 is in the communicatingstate using the wireless communicating system 2 shown in FIG. 5 (stepS31) information on the result of respective determination whether themobile terminal 3 is in the service areas of wireless communicationssystem 1 and 2, communication quality and field strength of thereceiving signals of the wireless communications systems 1 and 2, themoving speed and communication data rate of the mobile terminal 3 isupdated (step S32). Thereafter, a determination whether a switching(handoff) of WLAN service areas (cells) in the same wirelesscommunications system, that is the wireless communications system 2 isnecessary or not is made by detecting operation of peripheral accesspoints (APs) in WLAN service areas (step S33).

If it is determined that a switching is necessary (YES at step S33),switching between the WLAN service areas of the wireless communicationssystem 2 is conducted by switching the cells in the transceiver unit 239 b (step S34) and program sequence will return to processing at stepS32. On the other hand, if there is no necessity to switch between thecellular service areas of the wireless communications system 2 (NO atstep S33), a determination whether the mobile terminal 3 is also in theservice area of the wireless communications system 1 (step S35) is made.If the mobile terminal 3 is not in the service area of the wirelesscommunications system 1 (NO at step S35), then the program will proceedto processing at step S32 to continue the communication using thewireless communications system 2.

On the contrary, if the mobile terminal 3 is also in the service area ofthe wireless communications system 1 (YES at step S35), the moving speedof the mobile terminal 3 is detected by the moving speed detecting unit36. If the moving speed is equal to or higher than a predeterminedthreshold N, for example, equal to or higher than 50 km/h which is equalto said threshold M (YES at step S36), it is determined that use of thewide area wireless communications system 1 which can be used even if theterminal moves at a high speed provides merits to users and switching(handoff) from the wireless communications systems 2 to 1 isautomatically conducted (step S39). Alternatively, if the mobileterminal 3 is also in the service area of the wireless communicationssystem 1 (YES step S35), the communication data rate of the mobileterminal 3 is detected by the communication data rate detecting unit 35.If the communication data rate is lower than a predetermined thresholdK, for example, lower than 250 kbps (YES at step S36), it is determinedthat use of wide area wireless communications system 1 which enablesmedium and low data rate communication provides merits to users, so thatswitching (handoff) from the wireless communications systems 2 to 1 maybe automatically conducted (step S39).

If the mobile terminal is switched from the wireless communicationssystems 2 to 1 based upon the communication data rate which is detectedby the communication data rate detecting unit 35, switching may beconducted only if the moving speed which is detected by using the movingspeed detecting unit 36 is equal to or higher than a predeterminedthreshold N. In other words, it prepares for the possibility that evenif connection is switched to the wireless communications system 1 whichis suitable for medium and low communication data rate when the movingspeed is lower than said threshold N, then there is threat that thecommunication charge will become higher than that of the wirelesscommunications system 2, so that more economical wireless communicationssystem 2 is continuously used.

The condition whether the mobile terminal 3 is in the service area, themoving speed and/or communication data rate of the mobile terminal 3 andselection result of switching to the wireless communications system 1are displayed on the display unit 31 (step S37) enable the user toselect connection to desired wireless communications system prior toautomatic process of switching to the wireless communications system 2at step S39 as mentioned above (as shown by a dotted line in FIG. 5). Inother words, if the user enters from the input unit 32 an instruction toswitch the connection to the wireless communications system 1 accordingto the result of automatic selection based upon the result of a displayon the display unit 31 (YES at step S38), switching to the wirelesscommunications system 1 which is automatically selected is conducted(step S39). On the other hand, if the user enters an instruction tocontinue the connection with the wireless communications system 2, whichis different from the result of automatic selection result from theinput unit 32 (NO at step S38), the program sequence may proceed to stepS32 at which connection to the wireless communications system 2 iscontinued.

Foregoing wireless communications system, wireless communicationsmethod, wireless communications program, and program recording medium ofthe present invention provide advantages as follows: Wirelesscommunication can be conducted by automatically selecting an optimumwireless communications system for users depending upon the moving speedand communication data rate of a mobile terminal in the mobile terminalwhich is capable of dual radio communicating using any of a plurality ofdifferent wireless communications systems.

If a request for connection of wireless communication is made from auser when a user's mobile terminal exists in a service area which issimultaneously covered by a plurality of different wirelesscommunications systems, a wireless communications system having localservice areas is not selected when mobile terminal moves at a highspeed, but a wireless communications system having wide service areas isselected for connection, therefore it is possible to prevent frequentswitching (handoff) from occurring and to provide stable communicationservice. When the mobile terminal moves at a low speed, a wirelesscommunications system which is capable of high data rate communicationis preferentially selected for connection even if its service areas arelocal, thus, it is possible to obtain high data rate communicationservice.

If a user's mobile terminal is in a service area which is simultaneouslycovered by a plurality of different wireless communications systems andis in the communicating state and moves at a high speed, then the mobileterminal is connected with a wireless communications system having wideservice areas to continue the communication and it is possible to obtaina stable communication service and communication data rate. On the otherhand, if the moving speed is low, the mobile terminal is connected witha wireless communications system which is capable of high data ratecommunication and continues the communication, therefore, it is possibleto obtain high data rate communication service.

If a user's mobile terminal is in a service area which is simultaneouslycovered by a plurality of different wireless communications systems andis in the communication and communicates at low data rate, then themobile terminal is connected with a wireless communications systemadapted for medium or low data rate communication and conducts thecommunication, therefore it is possible to secure stable communicationservice and communication data rate. On the other hand, if thecommunication data rate is high, the mobile terminal is connected to awireless communications system in which high data rate communication ispossible to obtain high data rate communication service.

Even if a condition for switching from a wireless communications systemfor medium and low data rate communication to that for high data ratecommunication occurs based upon both the communication data rate andmoving speed due to the fact that the current communication data rate ishigh, connection with the wide area wireless communications system formedium and low data rate communication which can cope with high speedmovement is maintained without switching to obtain continuous and stablecommunication service. Even if a condition for switching from a wirelesscommunications system for high data rate communication to that formedium and low data rate communication occurs due to the fact that thecommunication data rate is low, switching to the wireless communicationssystem for medium and low data rate communication is avoided if themobile terminal moves at a low speed when the communication charge ofthe system for medium and low data rate communication is higher. Thus,connection with the local area wireless communications system which iscapable of high data rate communication is maintained therefore it ispossible to continuously obtain low charge communication service.

Selection condition of the wireless communications system can bepreliminarily presented to a user depending upon the moving speed and/orcommunication data rate of the mobile terminal prior to connection tothe wireless communications system, or prior to switching to thewireless communications system. Thus, connection to the wirelesscommunications system which is desired by the user can be conducted inaccordance with the user's determination.

1. A wireless communications system comprising: two different wirelesscommunications systems which are a first wireless communications systemfor medium and low data rate communication having a wide communicationservice area and a wireless communications system for high data ratecommunication having a local communication service area and mobileterminals which are connectable to any of said first and second wirelesscommunications systems, wherein said mobile terminals comprising: adetermining unit determining whether or not said mobile terminal is inthe respective wirelessly communicative areas of said first and secondwireless communications systems based upon determining signal strengthof a received signal; a moving speed detecting unit detecting the movingspeed of said mobile terminal; and a communication data rate detectingunit detecting the communication data rate of said mobile terminal; anda switching unit switching the connection of the mobile terminal withsaid first or second wireless communications systems based upon acomprehensive consideration of a result of determining whether or not inservice areas and a result of detection of said moving speed detectingunit and said communication data rate detecting unit, wherein if it isdetermined from a result of said determination of said determining unitand a result of comparison between said moving speed which is detectedby said moving speed detecting unit and said communication data ratewhich is detected by said communication data rate detecting unit andrespective preset threshold that said mobile terminal is to be connectedto said first or second wireless communications system, or thatconnection of said mobile terminal with said first or second wirelesscommunications system is to be switched, said determined result isinformed to a user together with said determination result and saiddetection result, so that said mobile terminal is connected to saidfirst or second wireless communications system which is selected by theuser.
 2. A wireless communications system as defined in claim 1, whereinif it is determined from a result of determination of said determiningunit that said mobile terminal is in the communicative service areas ofboth of said first and second wireless communications systems, then themoving speed of said mobile terminal which is detected by said movingspeed detecting unit is compared with a preset threshold; if said movingspeed is equal to or higher than said threshold, then said mobileterminal is connected to said first wireless communications system; and,if said moving speed is lower than said threshold, said mobile terminalis connected to said second wireless communications system.
 3. Awireless communications system as defined in any of claims 1 or 2,wherein if it is determined from a result of determination of saiddetermining unit that said mobile terminal is in the communicativeservice areas of both of said first and second wireless communicationssystems and said mobile terminal is connected with said first wirelesscommunications system so that it is in the state of communicatingtherewith, then the moving speed of said mobile terminal which isdetected by said moving speed detecting unit is compared with a presetthreshold; if said moving speed is equal to or higher than saidthreshold, the connection between said mobile terminal and said firstwireless communications system is maintained; and, if said moving speedis lower than said threshold, connection is switched to said secondwireless communications system by said switching unit.
 4. A wirelesscommunications system as defined in any of claims 1 or 2, wherein if itis determined from a result of determination of said determining unitthat said mobile terminal is in the communicative service areas of bothof said first and second wireless communications systems and said mobileterminal is connected with said second wireless communications system sothat it is in the state of communicating therewith, then the movingspeed of said mobile terminal which is detected by said moving speeddetecting unit is compared with a preset threshold; if said moving speedis equal to or higher than said threshold, the connection is switched tosaid first wireless communications system by said switching unit; and,if said moving speed is lower than said threshold, connection with saidwireless communications system is maintained.
 5. A wirelesscommunications system as defined in any of claims 1 or 2, wherein if itis determined from a result of determination of said determining unitthat said mobile terminal is in the service areas of both of said firstand second wireless communications systems and said mobile terminal isconnected with said first wireless communications system so that it isin the state of communicating therewith, then the communication datarate of said mobile terminal which is detected by said communicationdata rate detecting unit is compared with a preset threshold; ifcommunication data rate is equal to or higher than said threshold, theconnection is switched to said second wireless communications system bysaid switching unit; if said communication data rate is lower than saidthreshold, the connection with said first wireless communications systemis maintained.
 6. A wireless communications system as defined in claim5, wherein said switching operation to said second wirelesscommunications system is conducted if said moving speed of said mobileterminal which is detected by said moving speed detecting unit is lowerthan a preset threshold; switching operation to said first wirelesscommunications system is conducted if said moving speed is equal to orhigher than said threshold.
 7. A wireless communications system asdefined in any of claims 1 or 2, wherein if it is determined from aresult of determination of said determining unit that said mobileterminal is in the communicative service areas of both of said first andsecond wireless communications systems and said mobile terminal isconnected with said second wireless communications system so that it isin the state of communicating therewith, then the communication datarate of said mobile terminal which is detected by said communicationdata rate detecting is compared with a preset threshold; if saidcommunication data rate is equal to or higher than said threshold, theconnection between said mobile terminal and said second wirelesscommunications system is maintained; and, if said communication datarate is lower than said threshold, the connection is switched to saidfirst wireless communications system by means of said switching unit. 8.A wireless communications system as defined claim 1, wherein saiddetermined result is preliminarily informed to the user together withsaid determination result and said detection result prior to connectionor switching, so that said mobile terminal is connected to said first orsecond wireless communications system which is selected by the user. 9.A wireless communications system as defined in claim 1, wherein if it isdetermined from a result of said determination of said determining unitand a result of comparison between said moving speed which is detectedby said moving speed detecting unit and said communication data ratewhich is detected by said communication data rate detecting unit andrespective preset threshold that said mobile terminal is to be connectedto said first or second wireless communications system, or thatconnection of said mobile terminal with said first or second wirelesscommunications system is to be switched, said determined result isinformed to a user together with said determination result and saiddetection result, so that said mobile terminal is connected to saidfirst or second wireless communications system which is selected by theuser.
 10. A wireless communications method which is conducted in awireless communications system comprising two different wirelesscommunications systems which are a first wireless communications systemfor medium and low data rate communication having a wide communicationservice areas and a second wireless communications system for high datarate communication having a local communication service area and mobileterminals which are connectable to any of said first and second wirelesscommunications systems, the method comprising: determining whether ornot said mobile terminal is in the respective wirelessly communicativeareas of said first and second wireless communications systems basedupon determining signal strength of a received signal; detecting themoving speed of said mobile terminal; and detecting the communicationdata rate of said mobile terminal; and switching the connection of themobile terminal with said first or second wireless communicationssystems based upon a comprehensive consideration of a result ofdetermination whether said mobile terminal is in respective wirelesslycommunicative areas of said first and second wireless communicationssystem and results of detection of the moving speed and communicationdata rate of said mobile terminal, wherein if it is determined from aresult of determination whether said mobile terminal is in therespective service areas of said first and second wirelesscommunications system and a result of comparison between said movingspeed and said communication data rate and respective preset thresholdthat said mobile terminal is to be connected to said first or secondwireless communications systems, or that connection of said mobileterminal with said first or second wireless communications system is tobe switched, said determined result is informed to a user together withsaid determination result and said detection result, so that said mobileterminal is connected to said first or second wireless communicationssystem which is selected by the user.
 11. A wireless communicationsmethod as defined in claim 10, wherein if it is determined that saidmobile terminal is in the communicative service areas of both of saidfirst and second wireless communications systems, then the moving speedof said mobile terminal is compared with a preset threshold; if saidmoving speed is equal to or higher than said threshold, said mobileterminal is connected to said wireless communications system 1; and, ifsaid moving speed is lower than said threshold, said mobile terminal isconnected to said second wireless communications system.
 12. A wirelesscommunications method as defined in claim 10, wherein if it isdetermined that said mobile terminal is in the communicative serviceareas of both of said first and second wireless communications systemsand said mobile terminal is connected with said first wirelesscommunications system so that it is in the state of communicatingtherewith, then the moving speed of said mobile terminal is comparedwith a preset threshold; if said moving speed is equal to or higher thansaid threshold, the connection between said mobile terminal and saidfirst wireless communications system is maintained; and, if said movingspeed is lower than said threshold, the connection is switched to saidsecond wireless communications system.
 13. A wireless communicationsmethod as defined in claim 10, wherein if it is determined that saidmobile terminal is in the communicative service areas of both of saidfirst and second wireless communications systems and said mobileterminal is connected with said second wireless communications system sothat it is in the state of communicating therewith, then the movingspeed of said mobile terminal is compared with a preset threshold; ifsaid moving speed is equal to or higher than said threshold, theconnection is switched to said first wireless communications system;and, if said moving speed is lower than said threshold, the connectionwith said second wireless communications system is maintained.
 14. Awireless communications method as defined in claim 10, wherein if it isdetermined that said mobile terminal is in the communicative serviceareas of both of said first and second wireless communications systemsand said mobile terminal is connected with said first wirelesscommunications system so that it is in the state of communicatingtherewith, then the communication data rate of said mobile terminal iscompared with a preset threshold; if said communication data rate isequal to or higher than said threshold, the connection is switched tosaid second wireless communications system; and, if said communicationdata rate is lower than said threshold, the connection with said firstwireless communications system is maintained.
 15. A wirelesscommunications method as defined in claims 10, wherein if it isdetermined that said mobile terminal is in the communicative serviceareas of both of said first and second wireless communications systemsand said mobile terminal is connected with said second wirelesscommunications system so that it is in the state of communicatingtherewith, then the communication data rate of said mobile terminal iscompared with a preset threshold; if said communication data rate isequal to or higher than said threshold, the connection between saidmobile terminal and said second wireless communications system ismaintained; and, if said communication data rate is lower than saidthreshold, the connection is switched to said first wirelesscommunications system.
 16. A wireless communications method as definedin claim 14 or 15, wherein switching operation to said second wirelesscommunications system is conducted if moving speed of said mobileterminal is lower than a preset threshold; switching operation to saidfirst wireless communications system is conducted if said moving speedis equal to or higher than said threshold.
 17. A wireless communicationsmethod as defined in claim 10, wherein said determined result ispreliminarily informed to the user together with said determinationresult and said detection result prior to connection or switching, sothat said mobile terminal is connected to said first or second wirelesscommunications system which is selected by the user.
 18. A computerreadable recording medium having wireless communication program recordedthereon, when executed by a computer to perform the method of claim 10.19. A wireless communications system as defined in claim 10, wherein ifit is determined from a result of determination whether said mobileterminal is in the respective service areas of said first and secondwireless communications system and a result of comparison between saidmoving speed and said communication data rate and respective presetthreshold that said mobile terminal is to be connected to said first orsecond wireless communications systems, or that connection of saidmobile terminal with said first or second wireless communications systemis to be switched, said determined result is informed to a user togetherwith said determination result and said detection result, so that saidmobile terminal is connected to said first or second wirelesscommunications system which is selected by the user.